School of Environment, South China Normal University, Guangzhou, 510006, China.
College of Resources and Environment, Zhongkai University of Agriculture and Engineering, Guangzhou, 510550, China.
J Environ Manage. 2023 Aug 15;340:118004. doi: 10.1016/j.jenvman.2023.118004. Epub 2023 Apr 27.
The problem of co-contaminated soil at e-waste dismantling sites is serious and constitutes a critical threat to human health and the ecological environment. Zero-valent iron (ZVI) has been proven to be effective in the stabilization of heavy metals and the removal of halogenated organic compounds (HOCs) from soils. However, for the remediation of co-contamination of heavy metals with HOCs, ZVI has disadvantages such as high remediation cost and inability to take into account both pollutants, which limits its large-scale application. In this paper, boric acid and commercial zero-valent iron (cZVI) were used as raw materials to prepare boric acid-modified zero-valent iron (B-ZVI) through a high-energy ball milling strategy. B-ZVI coupled with persulfate (PS) to achieve simultaneous remediation of co-contaminated soil. The synergistic treatment of PS and B-ZVI resulted in the removal efficiency of 81.3% for decabromodiphenyl ether (BDE209) and the stabilization efficiencies of 96.5%, 99.8%, and 28.8% for Cu, Pb, and Cd respectively in the co-contaminated soil. A series of physical and chemical characterization methods showed that the oxide coat on the surface of B-ZVI could be replaced by borides during ball milling. The boride coat facilitated the exposure of the Fe core, promoted the corrosion of ZVI and the orderly release of Fe. The analysis of the morphological transformation of heavy metals in soils revealed that most of the heavy metals in the exchangeable, carbonate-bound state were transformed into the residue state, which was the key mechanism for the remediation of heavy metal-contaminated soils with B-ZVI. The analysis of BDE209 degradation products showed that BDE209 was degraded to lower brominated products and further mineralized by ZVI reduction and free radical oxidation. In general, B-ZVI coupled with PS is a good recipe for synergistic remediation of co-contaminated soils with heavy metals and HOCs.
电子废物拆解场地的复合污染土壤问题严重，对人类健康和生态环境构成严重威胁。零价铁（ZVI）已被证明可有效稳定重金属并去除土壤中的卤代有机化合物（HOCs）。然而，对于重金属与 HOCs 的复合污染的修复，ZVI 存在修复成本高、无法同时考虑两种污染物等缺点，限制了其大规模应用。本文以硼酸和商业零价铁（cZVI）为原料，通过高能球磨策略制备硼酸改性零价铁（B-ZVI）。B-ZVI 与过硫酸盐（PS）耦合实现了复合污染土壤的同步修复。PS 和 B-ZVI 的协同处理使十溴二苯醚（BDE209）的去除效率达到 81.3%，Cu、Pb 和 Cd 的稳定效率分别达到 96.5%、99.8%和 28.8%。一系列物理化学表征方法表明，B-ZVI 表面的氧化物层在球磨过程中可被硼化物取代。硼化物层促进了 Fe 核的暴露，促进了 ZVI 的腐蚀和 Fe 的有序释放。土壤中重金属形态转化的分析表明，大部分可交换态和碳酸盐结合态的重金属转化为残渣态，这是 B-ZVI 修复重金属污染土壤的关键机制。BDE209 降解产物的分析表明，BDE209 被还原和自由基氧化降解为低溴化产物并进一步矿化。总体而言，B-ZVI 与 PS 耦合是一种协同修复重金属和 HOCs 复合污染土壤的有效方法。
